New Cog VMs available

CogVM binaries as per VMMaker.oscog-eem.1288/r3319

Spur:

Implement remembered table pruning via ref counts.  The algorithm selectively

tenures objects to reduce the remembered table, instead of merely tenuring

everything.

Be selective about remembering tenured objects; actually scan their contents

before remembering willy-nilly.

StackVM:

Allow setting preemptionYields in the stack VM.

Cogit:

Use new register allocation in #== with V3 in order to limit register moves.

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